1. Technical Field
The present invention relates to compressors that may compress a refrigerant by utilizing a swash plate and particularly to compressors that may rotate the swash plate using a relatively lightweight structure. Such compressors may be utilized in air conditioning systems and more preferably in automobile air conditioning systems.
2. Description of the Related Art
One type of variable displacement compressor is disclosed in U.S. Pat. No. 6,010,312 and includes a swash plate coupled to a driving shaft disposed within a compressor driving chamber and pistons slidably inserted into respective cylinder bores. The end portion of each piston is engaged with the swash plate by means of a shoe. The swash plate is inclinably and slidably coupled to a rotor by a hinge mechanism. The rotor is fixed to the driving shaft. When the pressure within the driving chamber increases or decreases in order to change the inclination angle of the swash plate, the piston stroke is changed in response to the change of the inclination angle. As the result, the compressor output discharge capacity changes.
The hinge mechanism includes an arm that projects from the surface of the swash plate and a groove that is formed on the rotor surface. The arm is engaged with the groove such that the inner sidewall of the groove slidably contacts the outer sidewall of the arm. Thus, torque from the driving shaft is transmitted to the swash plate by means of the groove and the arm. When the inclination angle of the swash plate changes in order to change the compressor output discharge capacity, a bottom surface of the groove on the rotor may restrict the upper dead point (top clearance) of the piston to a constant position by slidably connecting the curved surface of top end portion of the arm. The hinge mechanism rotates together with the driving shaft and therefore, the hinge mechanism is required to be lightened in view of the centrifugal force exerted to the hinge mechanism due to the rotation together with the driving shaft. On the other hand, the hinge mechanism receives the reaction force of the piston in the axial direction of the driving shaft when the piston compresses the refrigerant and therefore, the hinge mechanism is required to have certain width in the rotating direction in order to reduce the unit area load that receives the reaction force. Such requirement with respect to the dimension of the hinge mechanism that receives the reaction force of the piston is contrary, to the requirement of the lightening of the hinge mechanism in view of the centrifugal force due to the rotation of the hinge mechanism. Further, when the reaction force of the piston becomes stronger, the width of the hinge mechanism is required to be wider and that made it difficult to reduce the weight of the hinge mechanism.
It is, therefore, an object of the present invention to provide compressors that may reduce the weight of the torque transmitting structure between the driving shaft and the swash plate.
Preferably, a compressor may include a suction port and a discharge port. The suction port may draw refrigerant into the compressor. The discharge port may discharge the refrigerant from the compressor. Further, the compressor may include a swash plate, a piston, a rotor and a hinge mechanism within a compressor driving chamber. The swash plate may be rotatably coupled to a driving shaft that is disposed within the driving chamber. The swash plate may rotate together with the driving shaft at an inclination angle with respect to a plane perpendicular to the driving shaft. The rotor may be connected to the driving shaft within the driving chamber. The hinge mechanism may connect the swash plate with the rotor and may transmit the torque of the driving shaft to the swash plate regardless of the inclination angle of the swash plate. The piston may be disposed in a cylinder bore and the end portion of the piston may be connected to a peripheral edge of the swash plate by means of a shoe. The piston may reciprocate in the cylinder bore to compress the refrigerant in response to the rotation of the inclined swash plate. Preferably, the piston may change the piston stroke to change an output discharge capacity of the compressor when the inclination angle of the swash plate is changed in response to the pressure state within the driving chamber.
In a preferred aspect of the present teachings, the hinge mechanism may include a projection and at least one arm. The projection may be disposed on either of the rotor and the swash plate. The arm may be disposed on the other of the rotor and the swash plate. The projection may have a recessed structure and the arm may be coupled to the projection to transmit the torque of the driving shaft. Because the projection may have a recessed structure, the weight of the hinge mechanism can be reduced and the projection can still provide sufficient width to receive the reaction force of the piston.
Other objects, features and advantages of the present invention will be readily understood after reading the following detailed description together with the accompanying drawings and the claims.